A bit about Red Bag as told to me by a vet that is easy to understand.
Think about the placenta as if the foal was encased in two socks. There's an
inner white sock that provides a cushion and protects the foal, and the
reddish sock has velcro all around the outer surface of the sock that attaches
to a surface on the lining of the uterus, through which nutrients, oxygen and
waste products are exchanged and then transported through the umbilical cord.
If the velcro prematurely separates, then all nutrient transport is stopped,
and that's why a previa placenta (red bag) is such a problem for foals.
During normal foaling, the white sock and foal push through a perforated area
in the red sock and then as the foal pushes through the pelvis, the white sock
rips and the foal is delivered free of both the socks. As the mare continues
to expel the placenta, the sock like structure turns itself inside out and
is presented in the shape of a mitten, as the pregnant horn is larger and the
nonpregnant horn of the uterus is much smaller. If you see the reddish
velcro life structure presenting before the foal is born, you're working against the clock, as oxygen transport has just been restricted.
The fetus develops within the "white" (i.e., amnionic membrane) sac and
it develops within the "red" (i.e., chorioallantois membrane) sac which
is attached to the uterine wall. Both are complete and closed sacs with
the "white" inside the cavity formed by the "red."
Also you can visit my website (link below) Part 1 and Part 2 on Red bag deliveries.
I am still working on Part 3.
Also Jos had sent me this article.Why perform a cytology smear in conjunction with a uterine culture? Its on his web site at
http://www.equine-reproduction.com/articles/cytology.shtml
Joyce
